Tuesday, September 1, 2020

Chapter 3 : Electromagnetism- Page 12

Chapter 3 : Electromagnetism

111. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon

A. number of turns of the coil
B. pole strength of the magnet
C. resistance of the coil
D. motion of the magnet

... Answer is ( C)



112. One Maxwell is equal to

A. 10⁻⁸ webers
B. 10⁴ webers
C. 10⁻⁴ webers
D. 10⁸ webers

... Answer is (D)


113. Susceptibility is positive for

A. ferromagnetic substances
non-magnetic substances
C. diamagnetic substances

D. none of the above

... Answer is (A)



114. Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per metre of length of each conductor will be

A. 10 N
B. 0.10 N
C. 100 N
D. 1 N

  ... Answer is (B)


115. A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T; the force on the conductor will be
Answer is (C)


116. A 200 turn coil having an axial length of 30 mm and a radius of 10 mm is ivoted in a magnetic field having a flux ensity of 0.8 T. If the coil carries a current of 0.5 A, the torque acting on e coil will be
4.8 N-m
B. 0.48 N-m
C.0.048 N-m
D. 0.0048 N-m

  ... Answer is (C)



117. An electromagnet has 50 turns and a rrent of 1 A flows through the coil. the length of the magnet circuit is mm, what is the magnetic field strength?

A. 500 AT/m
B. 250 AT/m
C.5 AT/m
D. 2.5 AT/m

... Answer is (B)


118. What is the magnitude and the direction of force per 1.1 m length of a pair of conductors of a direct current line carrying 10 amperes and spaced 100 mm

A. 22x 10⁻⁸N
B. 22 x 10⁻⁷N
C.22x 10⁻⁶N
D. 22 x 10⁻⁵N

... Answer is (D)


119. Biot-savart's law is a general modification of

A. Amperes law
B. Faraday's laws
C. Kirchhoff s law
D. Lenz's law
  ... Answer is (A)


120.  The retentivity (a property) of material for the construction of

non-magnetic substances
b. electromagnets

permanent magnets
D. transformers

  ... Answer is (C)



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